Friday, June 12, 2009

Matt Cawby: ZA001 being prepared for taxi tests

Matt Cawby, an Everett -area photographer got a picture of Boeing technicians installing the static pressue cone on the tail of the aircraft. This is an indication that taxi tests are very close! However I still do not have an indication of when taxi tests would start.

Matt Cawby's photograph


Anonymous said...

Isn't there something out of sync here. Is it possible that the taxi tests preceed the final gauntlet.

Flightblogger's detailed description of the path before flight included a period for the final gauntlet of several days with continuous engine operation followed the by taxi tests.

Do you think we are in for a surprise and they will reverse order?

Uresh said...

No, they're just preparing for the taxi tests. Tehy're still going to run final gauntlet before taxi tests but it may indicate that final gauntlet testing might be shorter than anticipated possibly becuase intermediate gauntlet testing went well though at this point I don't know. All test airplanes have to fly with the static pressure cone trailing behind the aircraft and they also need it with the taxi tests. They're just getting the airplane ready. It does indicate to me that taxi tests are pretty close to happening.

Gorbi said...

Hi Uresh, this is VERY interesting indeed. I just dug up some reference info on these static testing cones and here it is - I didn't know much about them before but now that I've read thru these paragraphs, I have a better understanding. Hope this helps anyone else who's interested!


Trailing cones were first developed and tested in the 1960's. Much of this early testing work conducted by the Royal Aircraft Establishment, Douglas Aircraft, the FAA, and NASA is used as the basis for RVSM certification efforts today.

Trailing cones give an easy way of calibrating the static pressure error of a pitot-static system. It does this by giving an accurate measurement of the ambient atmospheric pressure (static pressure). The trailing cone system consists of a cone that trails at least one fuselage length behind the aircraft via a high-strength pressure tube. Static pressure is measured forward of the cone by static ports. The cone stabilizes and aligns the ports relative to the freestream airflow. This design eliminates the cost and complexity of retraction mechanisms. This design can also be used on aircraft that cannot use more complex systems.

A general RVSM flight test includes not only the trailing cone system but also a task-specific test system that includes pressure transducers, recording devices (PC), and displays.

A trailing cone is a seemingly simple device. It consists primarily of a cone with holes drilled into it, plastic tube, static ports, and other miscellaneous parts. It might seem that such a device could be put together rather quickly with parts obtained from a local hardware store.

However, designing and producing a trailing cone that will operate without leaks and without failures at Mach 0.9 and -65° C requires a dedicated engineering and manufacturing effort. As the leader in flight test air data products, SpaceAge Control has undertaken the task of developing a trailing cone solution for RVSM certification and general flight testing.

Why are trailing cones so popular in RVSM certification work? Primarily because the FAA and JAA specify them as one of several methods that can be used to perform flight calibrations. The trailing cone method is the most cost-effective and easiest of the methods to perform. Below are excerpts from documents referencing the trailing cone method.

Anonymous said...

We have to thank Gorbi for this information which specifies the information about some aspects of the testing required on this plane.

I suppose that this is time saving in that the cone ultimately has to be attached to the plane and while the plane is waiting to start the final gauntlet tests, it is being prepared for what follows.

Maybe this signals that following the completion of the gauntlet testing, the plane can immediately move into taxi testing without waiting for time consuming preparations.

Anonymous said...

Is the flight cone used during the taxi tests?

I guess it will be dragged along the gound whether it is a real taxiing or a prectice testing

Gorbi said...

Maybe there's a retracting mechanism or perhaps a 'quick detach' feature which disconnects it for taxi test so that it's not shredded by the time it gets airborne for first flight.

But I agree ... it seems they're just doing some early preparation while the plane is sitting still.

Sure wish someone at Boeing would officially tell us what the heck is going on ... maybe they'll announce the first flight AFTER the plane has already landed ... LOL!

Rainer said...

The trailing cone can be clearly seen the Jon O's 777 video post from the other day